Circuit interrupter



y 20, 1947- w. M. LEEDS CIRCUIT INTERRUPTER Filed April 6, 1945 0 O 2 0 8 6 w, ,4 W m L m 1 w n 3137 4 m 00 a s A 33 W. W w fl rV- w w a aw o 3 m o o 3 a M n r 3 M Q W 00 {1 m a a m 4 a 7 4 H 1 R04 3 s 0 0 2 15 Z2 1 5 w 237% 49 4. w% a is W 0 4.0 O O 3 63 .44 8 2 34; 8 3 2 W. I f 3 1 I00 %J E 1 Patented May 20, 1947 CIRCUIT INTERRUPTER Winthrop M. Leeds, Pittsburgh, Pa.,

Westinghouse Electric Corporation,

assignor to East Pittsburgh, Pa., a corporation of Pennsylvania Application April 6, 1945, Serial No. 586,9il9

Claims.

This invention relates to circuit interrupters in general, and more particularly to circuit interrupters of the liquid-break type.

In a patent application filed April 3, 1945, Serial No. 586,354, by Winthrop M. Leeds and James M. Cumming, and assigned to the assignee of the instant application, there is disclosed and claimed a novel type of circuit interrupter utilizing first and second piston means, in which the first piston means forces fluid through a suitable interrupting structure against an interrupting arc, and the second piston means is operated by the pressure set up by a serially related pressure-generatlng arc. It is an object of my invention to improve the interrupting structures set forth in the aforesaid application.

Another object is to provide an improved circuit interrupter of the type drawing both a pressure-generating arc and an interrupting arc. I provide a first piston member movable in the interrupting chamber and a second piston member movable in the pressure-generating chamber with suitable connecting means for causing the simultaneous operation of both piston members.

Another object is to provide an improved circuit interrupter, in which an improved contactmounting arrangement is employed, whereby at least one of the contacts moves within a dashpot.

Further objects and advantages will readily become apparent upon a reading of the following specification, taken in conjunction with the drawing, in which:

Figure 1 is an elevational view, partly in section, of a circuit interrupter embodying my invention;

Fig. 2 is an enlarged vertical sectional view through the right-hand arc-extinguishing unit of Fig. l, the parts being shown in the partly open circuit position;

Fig. 3 is a view similar to Fig. 2, but showing the disposition of the parts in the fully closed circuit position of the interrupter;

Fig. 4 is a sectional view, taken along the line IV-IV of Fig.2; and

Fig. 5 is a sectional view, taken along the line VV of Fig. 2.

Referring to the drawing, and more particularly to Figure 1 thereof, the reference numeral i designates a tank, in which a suitable arcextinguishing fluid 2, in this instance circuitbreaker oil, is contained, filling the tank I to the level 3. The tank I has a cover 4 from which depend two insulating terminal bushings 5, through which extend terminal studs (not shown).

Threadedly secured to the lower ends of the terminal studs are contact feet 5 which support identical arc-extinguishing units, generally designated by the reference numeral 1.

Reciprocally operable in a vertical direction within the tank I is an insulating operating rod 8, to the lower end of which is secured a conducting bridging member 9 which serves, in the closed circuit position of the interrupter as shown in the full lines of Fig. 1, to electrically interconnect the two arc-extinguishing units I.

The unit '5 comprises an insulating casing H! in which is disposed an insulating plate I i rigidly secured in place by screws l2 to form a pressuregenerating chamber generally designated by the reference numeral i3 and an interrupting chamber generally designated by the reference numeral i i. A. first piston member i5, having formed therein. an orifice 16, moves within the interrupting chamber !4 being guided by the inner walls of the insulating casing Ill. A second piston member ll of annular configuration moves within the pressure-generating chamber i3. Insulating rods 58 interconnect the first and second piston members to cause their simultaneous operation. The upper ends of the rods l8 are threadedly secured to the piston IT. The lower portion of rods 18 are fixedly secured to piston 15 by pins liia.

The orifice construction is preferably follows the teachings set forth and claimed in U, S. patent application filed March 23, 1945, Serial No. 584,413 by Thomas E. Browne, Jr., and assigned to the assignee of the instant application.

A slide valve [9 moves within the pressure-generating chamber 13 to control venting means provided at both ends of the pressure-generating chamber [3 in the form of vents 20 and vents 2|. The slide valve I!) has integrally formed therewith flanges 22, 23 so that the second piston member l'i may effect the operation thereof. The contact foot 6 supports, in a resilient manner, a relatively stationary contact 24, suitable conductors 25 being provided to electrically interconnect the stationary contact 24 with the contact foot 6, which in this instance serves as a top cover for the casing 10.

An intermediate contact 25 is provided having a flange portion 21 which moves within a dashpot generally designated by the reference numeral 23 and formed by an insulating cylinder 29 secured in place to the insulating plate I in any suitable manner. Check valves 30 may be provided for the pressure-generating chamber l3 to close during high-pressure conditions therein and to open 3 during low-pressure conditions following a circuit interrupter opening operation. A compression spring 3| disposed between the plate H and a flange 32 integrally formed with the intermediate contact 26 serves to bias the intermediate contact 26 downwardly.

The intermediate contact 26, in the closed circuit position of the interrupter as shown in Fig. 3, engages with a lower movable contact 33, the latter being mechanically supported by a lost-motion connection 34 to a spider member 35 in which are threadedly secured the rods l8. The lower movable contact 33 has an extension 36 which is slidably guided through an aperture 31 provided at the bottom of the casing l and is engaged by the conducting cross bar 9 in the usual manner.

The lost-motion connection 34 comprises a compression spring 38 disposed between the spider member 35 and a flange 39 integrally formed with the extension 36 of the movable con tact 33. A flange i3 is integrally formed with the movable contact and serves to limit the downward motion thereof with respect to the spider member Check valves 4| may be provided for the region 42 below the first piston member 15 in the interrupting chamber Id,

The operation of the unit I will now be explained, In the closed circuit position, as shown in Figs. 1 and 3, the electrical circuit therethrough comprises contact foot 6, conductors 25, stationary contact 2d, intermediate contact 26, lower movable contact 33, through the conducting bridging member 9 and through the left-hand arc-extinguishing unit 7 in an identical manner. Upon the downward movement of conducting bridging member 9, the compression spring 38 causes a downward movement of the lower movable contact 33 with respect to the spider member 35 thus unpluggin the orifice 16. The accelerating compression prin 13 causes downward travel of both the first and second piston member l5, ll, they being interconnected by the rods l8. The downward movement of the first piston member l forces oil from the region 42 through the orifice [6 adjacent the interrupting are 44 drawn between the contacts 26, 33. The oil may then pass out of the interrupting chamber l4 through the vents 45 provided in the wall of the casing lfi. During this movement, the check valves 4| remain closed. Ihe provision of the dashpot 28 in which the intermediate contact 26 moves causes a separation between the contacts 24, 25, after the separation between the contacts 26, 33. This establishes a pressure-generating are 46 which establishes pressure within the pressure-generating chamber I 3.

During the interruption of high currents, the pressure created at th pressure-generating are 46 within the pressure-generating chamber l3 drives the second piston member I! downwardly to assist the accelerating compression spring 43 in forcing the first piston member l5 to provide a greater quantity of oil passing through the orifice 16 at increased velocity to interrupt the larger arc with greater gas formation which is formed between the contacts 26, 33.

Interruption soon follows and the continued downward movement of the first piston member l5 provides a flushing flow of oil through the orifice l6 and out the vents 45. At the extreme end of the opening travel of the second piston member H, the slide valve l9 closes the vents 2| and opens the vents 23, thereby permitting accumulated gas and contaminated oil to pass out of the pressure-generating chamber [3 through the vents 20. Upon the subsidence of pressure within the pressure-generating chamber l3, the check valves 30 open and fresh oil may flow into the chamber l3. The bridging member 9 may separate from the extension 36 of the lower movable contact 33 to introduce an isolating gap in the circuit.

During the closing operation, the bridging member 9 moves upwardly to pick up extension 36, and moves the contact 33 upwardly with respect to the spider 35 by virtue of the lost-motion connection 34, to plug the orifice l6 and raise both the first and second piston members l5, I! upwardly charging the accelerating compression spring 43. During this movement, oil is drawn in through the check valves 4| to thereby provide a fresh quantity of clean oil in the region 42 below the first piston member l5. Also, the upward movement of the second piston member I1 forces contaminated oil out of the pressure-generating chamber l3 through the vents 20. During this operation, the movable contact 33 strikes the intermediate contact 26 and raises the latter to effect an engagement between the contacts 24, 26 to effect a closing of the electrical circuit through the interrupter. At the extreme upward end of the travel of the second piston member H, the piston member l'l engages the flange 22 to raise the slide valve IE.- to cause closing of the vents 20 and opening of the vents 2!. The unit 1 is then in readiness for the next opening operation.

During the interruption of low currents, where the pressure established at the pressure-generat ing are 46 is not appreciable, reliance may be had upon the accelerating compression spring 43 to cause the necessary downward movement of the first piston member l5 to cause interruption of the interrupting arc 44.

The foregoing description discloses how I have solved the problem of increasin the mechanical driving power for the fluid moving piston l5 as the arc current is increased, the additional piston driving effort being derived from a seriallyrelated pressure-generating are 46. One of the most important novel features of the unit 1 is the valve arrangement which permits dirty oil to be flushed out and clean oil brought into both the interrupting chamber (4 and the pressuregenerating chamber l3. The pressure produced at the pressure-generating are 46 during highcurrent interruption is particularly effective during high currents in speeding up the motion of the lower piston and thus increasing the oil flow velocity in the orifice l6 so as to sweep away the larger volumes of gas which are formed.

It is to be observed that opening the breaker on no-load operation, that is, with no current passing through the breaker, permits the annular piston ii to draw clean oil into the pressure-generating chamber l3 through the check valves 30. Also, it is to be noted that excemive pressure in the pressure-generating chamber 13 will act on the upper edge 41 of the cylindrical slide valve 19 so as to open the exhaust ports 20 for emergency-pressure relief.

From the foregoing description, it will be apparent that I have provided an interrupter of improved construction, in which novel valve means are employed to circulate oil through the interrupter. It will also be apparent that I have provided novel interconnecting means, interconnecting the first and second piston means, the second piston means being actuated by a seriallyrelated pressure-generating arc.

Although I have shown and described a specific structure, it is to be clearly understood that the same Was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, means for establishing an interrupting arc, a first piston means for facilitating the extinction of the interrupting are, means for establishing a pressure-generating arc, a second piston means operated by pressure from the pressure-generating arc to assist the motion of the first piston means, and means rigidly interconnecting the first and second piston means.

2. In a circuit interrupter, means for estab lishing an interrupting arc, a first piston means for facilitating the extinction of the interrupting arc, means defining an orifice carried by the first piston means, means for establishing a pressuregenerating are, a second piston means operated by pressure from the pressure-generating arc to assist the motion of the first piston means, and means rigidly inter-connecting the first and second piston means.

3. In a circuit interrupter, an arc-extinguishing unit, a first piston member movable Within the unit, means biasing the first piston member to move to the open circuit position, a movable contact carried by the first piston member, a relatively stationary contact cooperable with an intermediate contact to establish a pressuregenerating arc, the intermediate contact being cooperable with the movable contact to establish an interrupting are, a second piston member operated by pressure created at the pressuregenerating arc to assist the opening motion of the first piston member, and means rigidly interconnecting the first and second piston members.

4. In a circuit interrupter, an arc-extinguishing unit, a first piston member movable Within the unit, means biasing the first piston member to move to the open circuit position, a movable contact carried by the first piston member, a relatively stationary contact cooperable with an intermediate contact to establish a pressuregenerating arc, the intermediate contact being cooperable with the movable contact to establish an interrupting arc, a second piston member operated by pressure created at the pressuregenerating arc to assist the opening motion of the first piston member, venting means to relieve the pressure created at the pressure-generating arc operated by the opening motion of the second piston member, and means rigidly interconnecting the first and second piston members.

5. In a fluid circuit interrupter, an arc-extinguishing unit, the unit comprising a pressuregenerating chamber and an interrupting chamber, means for establishing a pressure-generating are within the pressure-generating chamber and an interrupting are within the interrupting chamber, a first piston member movable in the interrupting chamber to force fluid toward the interrupting arc to facilitate its extinction, a second piston member movable in the pressuregenerating chamber and responsive to the pressure within the pressure-generating chamber, and connecting means for causing the simultaneous operation of both piston members.

6. In a circuit interrupter, an arc-extinguishing unit, the unit comprising a pressure-generating chamber and an interrupting chamber, a first piston member movable in the interrupting chamher, a second piston member movable in the pressure-generating chamber, connecting means for causing the simultaneous operation of both piston members, a stationary contact disposed in the pressure-generating chamber, an intermediate contact extending into both chambers, and a movable contact carried by the first piston member.

'7. In a circuit interrupter, an arc-extinguishing unit, the unit comprising a pressure-generating chamber and an interrupting chamber, a first piston member movable in the interrupting chamer, a second piston member movable in the pressure-generating chamber, connecting means for causing the simultaneous operation of both piston members, and means defining an orifice carried by the first piston member.

8. In a circuit interrupter, an arc-extinguishing unit, the unit comprising a pressure-generating chamber and an interrupting chamber, a first piston member movable in the interrupting chamber, a second piston member movable in the pressure-generating chamber, connecting means for causing the simultaneous operation of both piston members, means defining an orifice carried by the first piston member, and a movable contact carried by the first piston member by a lostmotion connection so as to plug the orifice during the closing operation.

9. In a circuit interrupter, an arc-extinguishing unit, the unit comprising a pressure-generating chamber and an interrupting chamber, a first piston member movable in the interrupting chamber, a second piston member movable in the pressure-generating chamber, connecting means for causing the simultaneous operation of both piston members, a stationary contact disposed in the pressure-generating chamber, an intermediate contact extending into both chambers, a movable contact carried by the first piston member, a dashpot, and the intermediate contact being movable in the dashpot.

10. In a circuit interrupter, an arc-extinguishing unit, the unit comprising a pressure-generating chamber and an interrupting chamber, a first piston member movable in the interrupting chamber, a second piston member movable in the pressure-generating chamber, connecting means for causing the simultaneous operation of both piston members, venting means at both ends of the pressure-generating chamber, and a slide valve for the venting means operable by opening and closing motion of the second piston member.

WINTHROP M. LEEDS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date I 2,020,475 Ronnberg Nov. 12, 1935 2,147,497 Prince et a1 Feb. 14, 1939 2,155,263 Flurscheim Apr. 18, 1939 

